1. Field of the Invention
The present invention is directed to a light-weight stable recreational vehicle chassis that can provide a stable platform for supporting the hull or superstructure of a recreational vehicle independent of the particular form or structure of the hull and, more particularly, to a recreational vehicle having a hull with side wall extensions that is not further required to provide structural strength to the chassis.
2. Description of Related Art.
As labor cost and fuel cost increase, there is a need to provide a chassis that can support a housing, hull or superstructure that can readily provide the options of extendable side walls to increase the interior space of recreational vehicles. The term “recreational vehicle” includes pullable trailers such as fifth-wheel trailers and travel homes with self-contained motors.
To increase the fuel efficiency of such recreational vehicles, there is a desire to provide a relatively light-weight chassis design that can still provide stability to the vehicle while maintaining rigidity, as well as increasing the storage space that is accessible from the outside of the recreational vehicle.
Motor homes are constructed in a variety of sizes and shapes and have been conventionally constructed with motor vehicle parts and components. As such, motor homes have been normally built on a chassis of a motor vehicle such as, for example, the Freightliner XC Class A motor home chassis that can be used with motor homes of up to 45 feet in length. Such a chassis can typically include a Cummins or Caterpillar diesel engine and automatic overdrive transmission. A pair of I-beams or other structural members are welded on such a chassis to provide sufficient rigidity so that the hull or superstructure can be constructed on top of such a chassis. The hull or superstructure is integrated with the I-beams or other structural members to contribute strength and rigidity and address the torsional stresses that can be generated by bending and twisting movements when the vehicle is in motion.
Problems have occurred when the bending and twisting motions have been transferred from the chassis to the shell, and it is frequently necessary for the shell or hull of the motor home to be sufficiently sturdy to contribute additional strength to the overall structure. As can be appreciated, by adding additional structural members in the shell to compensate for inadequacies in the chassis, this design approach further adds weight and increases the center of gravity of the vehicle. Compounding these problems is the desire to increase the storage space beneath the vehicle again without adding significant weight. An example of a motor home construction to address these issues can be found in U.S. Pat. No. 5,501,504.
The prior art has further attempted to use monocoque and semi-monocoque structures for both the chassis and the hull to reduce weight while increasing strength. Tubular steel cage infrastructures have also been proposed for the body and chassis of various forms of motor vehicles as a means of increasing strength and rigidity without adding significant weight. See, for example, U.S. Pat. No. 2,144,889, U.S. Pat. No. 4,045,075, and U.S. Pat. No. 6,205,736.
Of general interest is U.S. Pat. No. 3,989,119, U.S. Pat. No. 5,690,378, U.S. Pat. No. 5,921,615, and U.S. Pat. No. 6,343,830.
Recreational vehicles, including motor homes and trailers, have of recent years included extendable rooms or side wall units that permit the recreational vehicle, when stationary, to extend the walls of the recreational vehicle to increase the interior space. Frequently the recreational vehicle will be designed so that it is only functional when the side walls are extended for certain rooms in the recreational vehicle. Thus, a kitchen, bedroom or living room can be significantly extended to increase the living space for the occupants. Since a portion of the side walls must be extended, they cannot be relied upon to provide structural support for the chassis, and as larger areas of the side walls are extended or multiple sections of side walls are extended for one or more rooms, the ability to provide a contribution to the strength of the chassis section has been reduced.
Thus, there is still a need in the prior art to provide a chassis structure that can support various cargo or load configurations and not be dependent upon side wall strength. It is also desirable to provide basically a one-piece construction that will increase the under floor storage capacity while facilitating preproduction coating procedures such as dip processes and minimizing weight. Finally, it is desirable to provide a chassis that can serve as a solid stable platform regardless of the number and location of the side wall extensions that are desired for the hull or superstructure of the recreational vehicle.